1. School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
2. Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 2601, Australia
3. IRnova AB, Electrum 236, SE-164 40 Kista, Sweden
4. Microsoft Station Q, Delft University of Technology, 2600 GA Delft, The Netherlands
5. Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark